MAX6351 Maxim, MAX6351 Datasheet - Page 7

• Manufacturer Part Number: MAX6351
• Description: Dual/Triple-Voltage P Supervisory Circuits
• Manufacturer: Maxim

The MAX6358/MAX6359/MAX6360 include a WDI to
provide a reset if the µP goes into an infinite loop. After
a reset, the start-up timeout period and the initial time-
out period is nominally 46.4sec to allow the µP time to
initialize. After the first transition on the WDI and after
any toggle of the watchdog thereafter, the timeout peri-
od is nominally 2.9sec.
In some systems, it is necessary to ensure a valid reset
even if V
cuit shown in Figure 3. Note that this configuration does
not work for the open-drain outputs of the MAX6352/
MAX6355/MAX6358.
To monitor a negative supply rail using RSTIN or the
MAX6355/MAX6356/MAX6357, use the circuit shown in
Figure 4. In this configuration, a reset is issued when
the negative supply falls below V
Figure 3. Ensuring a Valid Reset Low to V
+3.3V/+3V +5V
CC
falls to 0. In these applications, use the cir-
Ensuring a Valid RESET Output
(MAX6358/MAX6359/MAX6360)
Applications Information
Monitoring a Negative Voltage
_______________________________________________________________________________________
V
V
MAX6351–MAX6360
CC
CC
5
3
GND
RST3
RST5
INTH
RST
Down to V
Watchdog Input
CC
.
5 and V
100k
CC
CC
3 = 0
= 0
µP Supervisory Circuits
Microprocessors with bidirectional reset pins will con-
tend with the push-pull outputs of these devices. To
prevent this, connect a 4.7kΩ resistor between RESET
and the µP’s reset I/O port, as shown in Figure 5. Buffer
RESET as shown in the figure if this reset is used by
other components in the system.
TRANSISTOR COUNT: 855
Figure 4. Monitoring a Negative Voltage
Figure 5. Interfacing to µPs with Bidirectional Reset I/O
V
CC
V
3
CC
V
IN
V
5
CC
5
MAX6351–MAX6360
V
V
Dual/Triple-Voltage
CC
CC
5
3
R1
R2
GND
RST3
RST5
RST
RSTIN
BUFFERED RESET TO OTHER SYSTEM COMPONENTS
MAX6355
MAX6356
MAX6357
Bidirectional Reset Pins
Interfacing to µPs with
Chip Information
4.7k
V
V
V
INTH
CC
CC
5 -
5 V
= 1.22 -
RSTIN
V
INR 1
R 2
RESET
R2
R1
GND
(V
P
CC
5 - 1.22)
7